1. Field of the Invention
The present invention relates to a stretchable conveyor belt and a method of producing the stretchable conveyor belt, and particularly to a conveyor belt suitable for conveying persons such as pedestrians and a method of producing the conveyor belt.
2. Related Art Statement
In a recent aging society, there has been a strong demand for barrier-free facilities.
A pedestrian overpass having stairs provides a barrier to old people. To solve this problem, there has been proposed to replace the stairs of the overpass with a curved-path pedestrian conveyor belt which can be moved up and down along a spirally curved loop path. This conveyor belt will release pedestrians from going up and down the stairs.
In addition, in a recent speed-up society, there has been a demand for conveying pedestrians at a high speed. In particular, there has been a strong demand for a variable-speed pedestrian conveyor belt which can be moved at variable speeds.
At specific locations where pedestrians step onto, and off, the variable-speed pedestrian conveyor belt, the conveyor belt can be moved at low speeds; and at other locations than those specific locations, the conveyor belt can be moved at high speeds. Thus, the conveyor belt can convey the pedestrians at increased speeds.
However, a conventional belt includes a belt-reinforcing material, such as a reinforcing canvas sheet or steel cords, that is embedded therein to provide a lengthwise tensile force thereof. Therefore, the conventional belt has substantially no lengthwise stretchability and accordingly cannot be used as the above-described curved-path pedestrian conveyor belt or variable-speed pedestrian conveyor belt.
FIGS. 26A and 26B show examples of the conventional belt. FIG. 26A shows a belt including tension canvas sheets 200, each as a belt-reinforcing material, that are embedded therein; and FIG. 26B shows a belt including steel cords 202, each as a belt-reinforcing material, that are embedded therein.
In those figures, reference numerals 204, 206 and 208 designate an upper cover rubber, a lower cover rubber, and a cushion rubber.
When the curved-path pedestrian conveyor belt is moved along a curved portion of the loop path, a widthwise inner half portion of the conveyor belt needs to contract in a lengthwise direction of the belt, and a widthwise outer half portion of the belt needs to stretch in the lengthwise direction. However, in the conventional conveyor belt, the tension canvas sheets 200 or the steel cords 202 as the belt-reinforcing members are embedded in the rubber layers such that the canvas sheets 200 or the steel cords 202 are extended out and binds the rubber layers in the lengthwise direction over the entire width. Thus, the conventional belt cannot be moved along the curved portion or portions of the loop path.
Where the specific locations where pedestrians step onto, and off, the variable-speed pedestrian conveyor belt, the conveyor belt needs to be stretched out in the lengthwise direction over the entire width; and at other locations than those specific locations, the conveyor belt needs to be contracted in the lengthwise direction over the entire width. However, for the same reasons as described above, the conventional belt cannot be moved in that manner and accordingly cannot be used as the variable-speed pedestrian conveyor belt.
While the problems of the pedestrian conveyor belts have been described above, those problems commonly occur to the curved-path conveyor belts and the variable-speed conveyor belts.
Thus, a curved-path or variable-speed conveyor belt needs to be formed such that widthwise opposite side portions of the belt have a lengthwise stretchability or such that an entire width of the belt has a lengthwise stretchability. However, there remains the problem of how to form the conveyor belt.